Process and apparatus for catalytic conversion of hydrocarbons



March 20,'1951 I G G oBERFr-:LL ET AL 2,546,042

PRoCEss'ANi: APPARATUS FOR CATALYTIC CONVERSION 0F HYDROCARBONS Filed Dec. 51. 194s bons.

Patented Mar. 20, l,1951

UNITED STAT/Es PATENT OFFICE `PROCESS AND APPARATUS FOR CATALYTIC 'CONVERSION OF HYDROCARBONS ('eorgezGrover{Oberlell and George N;.Cade,\Bar -tlesville,` Okla., assignorsgto Phillips `:Petroleum Company, a corporation of Delaware ApplicationfDecember 31, 1948, SeralNo.f68,464

This invention relates to amethod of :and apparatus `for Vcat'a'.lytically. .converting :hydrocar- In a `.more Aspecific -faspect :fit relates fto a method of and apparatus'for catalytic cracking of gas oil stocks.

In .accordance with `rour invention, hydrocarbons are y-catalytically `converted-in fan -.elongated reactionvesselain which fuel'gasesrfiowin -af'spiral path around .an :axially `moving .hydrocarbon stream containing Val .iinely divided catalyst, thereby to 4heat :such hydrocarbon stream `to lconversion temperature. A streamuof inertgases is introduced tangentially into A`the spira-lly mov,- ing fuel gas :stream as it passes from the conversion zone to a regeneration :;fzone, thereby `to cool the :fuel gas stream tofregenerationztemperature. In the regeneration zone, :amajoriportion of the c-atalystinthesfeedfstream is Aforced into the `outer spirally vmoving .gas stream lby :centrifugal action rand-regenerated. This regenerated catalyst, togetherzwith most: of lthe `incl-gases, and a minor portion-of converted hydrocarbons, are removed from the :peripheralregions Yoi `the ureactor, v:while la Vmajor eportion of ithe converted hydrocarbons :and a minor lportion of fuel `gases andtunregenerated catalyst :areaemovedvfrom the central-region of '.thereactor. AThewunregenerated catalyst is passed :through .a "regeneration 4zone and recycled together with the .regeneratedcatalyst withdrawn .from the peripheral :regions of the reactor. The rgaseous eiiluent from thereactor, consisting of Aa Ymixture of fuel gases and converted hydrocarbons, is separated fin-any suitable mannerffor productrecovery. I

The vmethod and apparatus of this invention are particularly applicable to endothermic catalytic conversion of hydrocarbons, 4such as catalytic cracking and Vcatalytic dehydrogenatiombut they also nd applicationin other 'typeszof .catalytic reactions, such as hydroforming, isomerization, polymerization, rand alkylation .of fhydrocarbon feed stocks. The novel apparatus and method of 'the present invention K.permit ithe ,conversion reactions .to :be conducted `-iat .fhigh throughput v:while the 'tangential introductionfof the Vfuel' gases provides :highly '.eicient fheat transfer between the ifuel :gases and 'the hydrocarbon vstreamlto.bec'onverted It is an 'object of .our invention .to vprovide an improved method of Vand apparatus :for catalytically convertingshvdrocarbons.

`it is ag 'further Yohjectcf four :invention to 'effect such catalytic Yhydrocarbon conversions at high throughput yand A.with jveryfe'ihc'ient V:heat vtransfer in endothermie reactions.

fItis afurther .object of our 'invention to pro'- vide va method of and apparatus `for effecting catalytic conversion and Acatalyst vregeneration in asingle reaction vessel. f

Various other objects, advantages and features of "our invention will Abecome apparent' to those skilled in the -artfrom the following description, taken :in vconjunction with the accompanying drawing, in-which the ligure is a flow diagram of a typical catalytic cracking system in which our novel .reactor shown 'in vertical section.

Referring now to the drawing in detail, we'have showna cylindrical reactor I 0, preferably formed from steel, of the type utilized in'the manufac-l ture of carbon black. The interior of the vessel is divided into a conversion zone, generally indicated by vreference character Il, a regeneration zone, generally indicated .by reference numeral I2, and a separation or withdrawal zone, generally indicated by reference numeral I3. The vessel 10 l'is provided with a shell o1- lagging I4 of refractory heat 'insulating material, such as magnesia 0r asbestos, which "is disposed about theconversion zone I'I. A tube or sheath I5 of a heat exchange material, such as steel, is disposed `within the conversion zone II and is secured, in any suitable manner, to the adjacent end `of fthe 'vessel I0. Preferably, this tube is cylindrical and kis disposed concentrically with respectfto 'thelcylindrical portion of the reaction vessel. This 'tube permits Aeiiicient heat transfer between an 'axially moving feed stream and tangentially'introduced fuel gases while prevent ing intermingling of these two streams Within the conversion zone.

Feed stock .is "introduced interiorly ofthe tube I5 through a conduit II terminating in a nozzle I8. The hydrocarbon portion of the feed stock to vbe Yconverted isfed to conduit I1 through a valve I9; steam vmay be admitted to conduit I'I through a 1ine'20 controlled by a valve 2|; and suspended finely divided catalyst may be introduced into conduit Il through aline 22 controlled bya valve 23. Alternatively, the catalyst may be introduced interiorly of the tube I5 through manifolds 24 by aline 25 and valves 26. Preferably, the manifolds are arranged symmetrically with respect to the axial conduit I1 through `which the vfeed stock is introduced.

"In accordance with the invention, a large variety Vvof feed stocks may Vbe introduced by conduit I1 for catalytic conversion within the reactor -i'Il. A preferred feed stock consists of a 400 -t 750 F. gas oil, in which case the catalyst may be any highly active -nely 'divided ymaterial such as silica-alumina, or silica-zirconia. The catalyst particles may have a size of 100 to 300 mesh, and the catalyst to feed ratio may vary between 1 to 20 pounds of catalyst per gallon of oil. The same type of catalyst may also be used for catalytic cracking of other hydrocarbon feed stocks, such as naphtha, light hydrocarbons, or kerosene stocks. The present invention is also applicable to the reforming of gasoline, and to the aLrylation of aromatic compounds, such as benzene, by oleins, such as ethylene, in which case the catalyst may be cadmium pyrophosphate. In the polymerization of olefins, such as ethylene, the catalyst may consist of phosphoric acid suspended on silica or kieselguhr. In the catalytic hydrogenation of olens to form p'arainns, the catalyst employed may be nickel or cobalt on silica or silicaalumina.

As will be apparent from the drawing, the finely divided or huid catalyst may be suspended in a vaporous or liquid hydrocarbon feed of the character described by introducingcatalyst into the conduit I'I through valve .23. Alternatively, at least part of the catalyst may be separately chargedv to the conversion zone I I through valves 26 and manifolds'24. Steam may be added, if desired,gthrough:-line andvalve 2| to facilitate Vaporization of the feed stock before it is introducedinto the reaction vessel. Y

It will be vapparent that the feed stock introduced into the vessel in the manner described travels. axially through the conversion zone II `and the regeneration Zone I 2 to the separation zone I3.

In accordance with the invention, fuel gas is charged into the annular Zone 2l between tube I5 and the vessel `I0 through tangentially directed'inlets 2x3 and 29 which are connected, respectively, through valves 30, 3l to a common supply conduit 32 which is controlled by a valve 33. In the embodiment shown. we have provided two such inlets axially spaced from each other but we may utilize any desired number within wide limits and they maybe spaced at intervals around the circumference of the vessel, if desired,

provided that all inlets Aare directed so as to pro-l vide concurrent iiow of the several gas streams. The fuel gas consists of a mixture of a fuel, such as natural gas, and air in proportions to be later described.Y It will be apparent that the stream of fuel gases travels in a generally spiral path about the peripheral region of the reaction vessel, passing successively through the combustion zone 21, the regeneration zone I2, and a peripheral region- 35 ofthe separation zone I3.

The combustion ofthe fuel gases entering the reactor releases sufficient heatrto provide a temperature of 800 to 1050 F. within the conversion zone for catalytic cra-cking reaction of gas oil feed stocks. Combustion of the fuel gas within the annular zone 2'! produces a spirally moving flame about the tube I5 and, by the eiiicient heat transfer through this tube, the feed sto'ck within zone II is heated to conversion temperature. The proportion of Iair or oxygen in the fuel stream should be sufficient to cause complete combustion of the fuel gas to carbon dioxide and water, and to produce 'an uncombined oxygen content of about 1 to 2O volume per cent in the combustion product gases passing from the annular zone 2'! into regeneration zone I 2.

In this manner, the hydrocarbon feed `stock is converted within zone EI, and the effluent from this zone, therefore, consists of converted hydro- 4 carbons and spent catalyst having a deposit of carbon thereon. In the regeneration zone I2, a major portion of the spent catalyst is forced into the peripheral region of the chamber as a result of the helical motion of the fuel gases passing from annular zone 21. In accordance with the invention, a cool inert gas or diluent, such as nitrogen, is added tangentially to the reactor through inlets 36, 3'1 which are connected, respectively, through valves 38, 39 to a supply conduit 40 controlled by a Valve il I. These cool inert gases are added to the spirally moving combustion gas stream in a suihcient proportion vas to cool thisl stream to a catalyst regeneration temperature within the range of 950 to 1150* F. Accordingly, a portion of the spent catalyst is regeneratedin the zone I2 and passes in a spiral path to region 35 of the separation zone, along with a major portion of the inert gases and combustion gases, and a minor portion of the converted hydrocarbons. Y Y

The bulk of the converted hydrocarbons passes axially through the "regeneration Zone to a central'region 43 of withdrawal zone I3. The converted hydrocarbon stream passing into the region d3 also contains a portion of spent or un regenerated catalyst together with a minor por-v tion of the fuel and inert gases tangentially charged to the reactor. The regions 35, 43 of withdrawal zone I3 areseparated by a cylindrical bafe or guide 44 which collects the fluid from the central region of the Vessel, and this effluent is withdrawn through a conduit 45 and passed to a separator 46,such as a cyclone separator. The effluent from the peripheral region 35 is withdrawn through a conduit 41 and charged to a second separator.

The pressure within the reaction vessel may vary within wide limits depending on the nature of the stock to be converted and the other reaction conditions. In general, the pressures used vary from l5 to 500 pounds per square inch. The reaction time within conversion zone I I may also be varied within `wide limits by changing the length of the reaction zone and the velocity with which the reactants are introduced. In general, this reaction time may vary from 0.001 second to one minute. The velocity of the gases and length of regeneration zone I2 are controlled so that the regeneration time is sufficient to remove from 50 to 901per cent of the carbon from the spent catalyst. This oxidation of carbon deposited on the catalyst is effected by the residual oxygen contained in the combustion gas stream passing into the regeneration zone I2. If necessary, the oxygen content of the regeneration gases may be increased to any desired value, for example 0.5 to 5 per cent, by adding additional oxygen with the inert gas introduced through inlets 36 and 31. Additional cooling of the fuel gases within the conversion zone may be effected by. withdrawing heat through the walls of the reaction vessel at the regeneration Zone I2. It Will be noted that this region of the vessel is surrounded by thinner heat insulating material, or in some cases almost none, and, accordingly, at least a portion of the heatv produced by the exothermic regeneration reaction may be withdrawn and utilized, for example, by disposing heat exchange coils around the exterior of the vessel so that the heat from the regeneration reaction is utilized to raise the temperature of a gas or liquid stream at some other part of the process. Specifically, this heat exchange system maybe used to preheat the charge stock introduced through conduit I'I.

asfpreviously stated off a: maior :portion *of con` vertedz hydrocarloonsia. minor.x portion of: fuel. and 'inertzgasesyland arminoraportionl .ofiunregenerated catalyst; i It', Willi be: understood that the converted." hydrocarbons; justt referred." to includerthe compounds .in the! feed? stockl which areinotrconverted in the= reaction zone H'. In separator 46, the. solid catalyst particles and gases arelseparated, the-.catalyst passing; through aline. '0, yalve.5'l,- regenerationr Izone .52s. valveA 53; and line '54' to :recycle-line 5i The spentA catalyst passing from. the:fsepa-ratrnr.` itV is. `thus regenerated Yand'A recycled. Invscrnefcases, Where a :substantiall quantity# of:y regenerated;catalyst:is: recycled'fffrom.k separator 48; itis.v .notnecessary.` that .the mnOrpOrtion oflcatalyst.:separatedliin tha-unit 46 be regenerated. Thus, for example, Wllen; azmin'ori portion: :of this :spent catalyst .isf

mixed with. a. major.- portion; .of regenerated catalyst,..the:oyera1l carbon. content.- of the; mix.- ture may' bezsuflicientlyf lovv. as to permit; efcient conversion in the zone II. this. case, .the catalyst separated. in uniti te. is: passed. directly to recycleY line. through. aline: 565i anda Valve 51.'4 If; desired; spent catalyst: from theunit'l' maybe directlywithdrawn throughA valve 53 and; outletz' while fresh. catalystm'ay be: admitted: throughinletil and val-'ye 6l: tozrepl'ace. losses due .tofnnes leaving the system with. the: product. gases;

In somecas'es; it is desirablefto'. feed astrippingv gastsuc'h as: steam to: the-separatordlL To this end,. an: inlet 55|'. is. provided' fonthe stripping gas; which passes; into 'thee separatorl througlr a valreiSZa Accordingly;the-.gaseous product-*from the.; separator: 61 consistsl ofi a. major: portion of converted hydrocarbons, a minor portion: of fuel and inert gases; and steam: which may be ad-t mitted to.. the system either through valve; 62- or through valvea21lratthe'inlet toreactor lil. This` gaseous mixture. isaeharged'i through a. line .63., an. automatic4 control. valver. 641 and a" line.:l 65 to: a condenser. 66 in: which thes'steam. isi condensed andremoved'.l as. a liquidphase throughline l'l.` and valve 68. The: product. lronfrA the. condenser 65,. consistingof converted' hydrocarbons, combustiorr gasesA and` inert gases-is charged `through a line'. B95 toa separation Zonea lil', In this sepa.- ration zone, the hydrocarbon'containing; mixture is; separated into an: overhead' product? consisting ofmethane, nitrogen, hydrogen, yand other-light gases 'whichVV iswithdrawn-.through a valved outsl'ett'l I z. Lighthydrocarbons; such as thosefconf-4 taining. 3 and 4f. carbon. atoms are withdrawn; throughl valved outlet l2," a'V gasoline; fraction-is Withdrawn through valved outlet 1.3, andra gas' oil; fraction is Withdrawn through. valved outletl 'ML for recycling: tothe feedi conduit: lil. The. bottoms product from yseparation Zone fr.. vvhicl'ry is'withdrawn through Valved outlet; l5; consists ef' heavy residuali products..

Y Theceluent chargedto separation Vunit lanen-- sists, as statedgpf amajor portion oftregenerated catalyst.: afrninorr portion ofi.; converted. hydro.- earhons. and the.; maior-'portion 'or fthe; fuel? and` inertigases'.. inthe;` separatori 43,:thef finely, divided." ^regenerated `c'atalysti ist Withdrawn. a: line 'l-Tl; andi avalve 'i8 .for passage; to; the recycle conduit: 25:; The.V gas yfronzthe. sepairation`4 413; consisting.' primarily-,of fuelgands, inert: gases.- `Witl'lssomee converted lrydrzocarloons;A is passed; through aline.. lt; to ualye: 611;, condenser? Gfi.; and; separating, Zone.; .l l1:` Where.V it isseparated; .itaicon'rponents thezmannenzpreriousln 6 descrihedfirr connection"v Withfthe: gaseousproduct from separatorli.

`In theoverall operationrof'thessystem;v itzwill'.

benoted thata stream. of hydrocarbongfeed stoel;l containingk suspended, finely; divided catalyst: is passed. in anraxiafr path. into..'conrersionszoney .|I., Where.: it: i's;.irai'sed to rrconrersion. temperature.. by heatiexchange with. hotcombustion gases. through tube: I5; which. prevents4 interminglingzoft the -eedi streamand. combustion: gases.. inithe corr.- version. zone.. Hydrocarbons .are thus converted catalytically,l and. passed into; regeneratonzone i2; where.; some intermingling; between. the: come bustion gases and converted. hydrocarbon .stream occurs. :Inthisv zone,` aV maiorporton onthecatalyst` moves to the periphery. of thervessel; into Contact' with: the combustion gases; a. coolantv beingadded. through inlets 36. and. 3l'- toredu'- the-temperature; of the'fuelgases to regenera-fr tion temperature. In this. manner, thema-501'. portion of the catalyst: is regenerated through removal. of carbonaceousdeposits therefrom and this regenerated catalyst, together with. thefuel and. inert gases, passes throughregion 35.-of..separ ration zone i3, and. is fed toseparator 48. The. converted hydrocarbons', together with a. minor portion. of unregenerated catalyst` andf a minor. portion of fuel and inert-gases'pass.'through-,the central region 1370i separation vzone i3 tothe separato1-46- The separators; it-and 48., the oondenser 65, and the separationzone 'lll aresoconf. nected as to separate and recycle. the. catalyst, and .separate,..the. converted hydrocarbons, fuel. gases, andinertgases intetheir respectivefcome ponente. The tangential. iiamein .tliefzone` 21. transfers. its heatY very effectively. through. the tube and' the spiralmotion. of. thefuel-gases and inert gases provide a swirling motion. and turbulence ofthe gases in the regeneration zone so that' the carbonaceous deposits are rapidly burned 01T the hydrocarbon particles.

It will be noted thatV the outside; of the reactor.` around the cracking'zone is insulated, Whereas.` that around the regeneration'zone; islesssinsur lated orV freeI from insulation. This arrangement is in accordanceY Withthe facts that the cracking reaction is endothermic, and` the regenerationA isl eXother-mic. Part of theheat produced by the eX-othermicregeneration reac' tion isi-intentionally lost through the reactor WallsK surrounding regeneration. Zone l2", -andanother partdofthis. heat may' effect,A some' `additional cracking or reforming ina.the.'centra1;.regi'on of;` the regeneration. zone..

.Ltwill lie/apparent that: reactor 2 need notbe absolutely cylindrical.A In'. fact; it may. advan-y tageously be. conical or. exponentially vflaredvvith increasing, crossrsectional area in the. directionof flow.. .This design provides 'increased control of, ow Velocity, whichmay be increased in some cases hy the addition of :inert gas 'throughzimani'-A folds 36g and 3l.

As.. a specic.exanuila. a; cracking stock.; such as ceduti-1750.9 Fr virgin gasgoil enters reactor [Il through; inlet. I8; .The gasaoilmay be. vaporized:

zirconia cracking catalyst having a particle size of 100 to 300 mesh enters the reactor through inlet I8 or manifolds 24. The mixture of oil vapor and suspended catalyst passes through sheath I5 and a fuel gas consisting of a mixture of natural gas and oxygen enters reactor Hl tan'- gentially through manifolds 28, 29 and produces a helically traveling flame around sheath l5. The proportion of oxygen entering through inanifolds 28, 29 is sufficient to eiect complete combustion of the fuel gas to carbon dioxide and water and to produce a helically traveling combustion-product gas containing about 1 to 20 Volume per cent uncoinbined oxygen. The helical iiame around sheath I5 rapidly and e'ciently heats the gas oil-catalyst mixture to a cracking temperature within the range of 859 to 1050 F. The ratio of fuel-air mixture to gas oil-catalyst mixture is easily regulated to obtain such a temperature inside sheath l5.

When the catalyst suspended in hydrocarbon vapor emerges from the open end i sheath t5, the major part cf the catalyst is thrown toward the walls of reactor IG and into the combustion gases traveling helically along the reactor walls. This action is a result of the helical motion of the gases in the reactor. Sufficient nitrogen is added tangentially through manifolds $6, 3'? to cool the peripheral gases to a regeneration temperature within the range of 950 to 1150" F. This cooling is rapidly eiected by virtue of the swirling motion and high turbulence of the gases. The catalyst passing into the peripheral gases is rapidly regenerated by the free oxygen, which burns off carbonaceous deposits. The oxygen content of the peripheral gases may be further adjusted to any desired value, for example 0.5 to 5 per cent, by adding supplemental oxygen with the inert gas through manifolds 36, 3l. The catalyst is regenerated and recycled in the manner previously described, and products consisting of light gases, a C3 and C4 light hydrocarbon fraction,a gasoline fraction, a recycle gas oil fraction, and a heavy residual fraction are withdrawn through the respective outlets of separation zone lll.

While the invention has been described in connection with a present, preferred embodiment thereof, it is to be understood that this description is illustrative only and is not intended to limit the invention, the scope of which is dened by the appended claims.

Having described our invention, we claim:

l. In the art of catalytically converting hydrocarbons, the steps which comprise passing a stream of hydrocarbon feed stock containing suspended, nely divided catalyst into a conversion zone and then into a regeneration zone, passing a stream of hot regeneration gases in a helical path around the hydrocarbon stream in said conversion zone and in heat exchange relation therewith, thereby to heat said hydrocarbon stream to Vconversion temperature, cooling said gases to regeneration temperature as they pass from the conversion zone into the regeneration zone, withdrawing converted hydrocarbons and unregenerated catalyst from the central region of the regeneration zone, and withdrawing converted hydrocarbons and regenerated catalyst from the peripheral region of the regeneration zone.

2. In the art of catalytically converting hydrocarbons, the steps which comprise passing a stream of hydrocarbon feed stock containing suspended, nely divided catalyst into a conversion zone and then into a regeneration zone, passing a stream of hot regeneration gases in a helical path around the hydrocarbon stream in said conversion zone and in heat exchange relation therewith while preventing contact between the hydrocarbon stream and the gas stream, thereby to heat said hydrocarbon stream to conversion temperature, cooling the helically-moving gases to regeneration temperature as they pass from the conversion zone to the regeneration zone While permitting intermingling of the hydrocarbon stream and the gas stream, withdrawing converted hydrocarbons and unregenerated catalyst from the central region of the regeneration Zone, and withdrawing regenerated catalyst from'the peripheral region of the regeneration zone.

3. In the art of catalytically converting hydro-` carbons, the steps which comprise passing a stream of hydrocarbon feed stock containing Suspended, finely divided catalyst into a conversion zone and then into a regeneration zone, passing a stream of hot flaming regeneration gases in a helical path around the hydrocarbon stream in said conversion zone and in heat exchange relation therewith while preventing intermingling of the feed stock and gas stream, thereby to heat said ieed stock to conversion temperature, passing the helically-moving stream of gases into the regeneration zone while permitting catalyst to pass from the feed stock into the combustion gas stream, introducing a stream of inert gas into the regeneration zone in tangential relation' to the helically-moving stream of combustion gases to cool it to regeneration temperature, withdrawing converted hydrocarbons and unregenerated catalyst from the central region of the regeneration zone, and withdrawing converted hydrocarbons and regenerated catalyst from the peripheral region of the regeneration zone.

4. in the art of catalytically converting hydrocarbons, the steps which comprise passing a stream of hydrocarbon feed stock containing suspended, nely divided catalyst successively into a conversion zone, a regeneration Zone, and a separation zone, passing a stream of hot regeneration gases in a helical path through said conversion zone, said regeneration Zone, and said separation zone while preventing intermingling of the feed stock and gases in the conversion Zone but permitting passage of catalyst from the feed stream to the regeneration gas stream in the regeneration zone, introducing a stream of inert gas into the regeneration zone in tangential relation to the stream of hot gases, thereby to cool said regeneration zone to regeneration temperature, withdrawing converted hydrocarbons and unregenerated catalyst from the central region of the separation zone, and removing converted hydrocarbons and regenerated catalyst from the peripheral region of the separation Zone.

5. In the art of catalytically converting hydrocarbons, the steps which comprise eifecting helical movement of a stream of hot regeneration gases through a conversion zone and a regeneration Zone, passing a stream of hydrocarbon feed stock containing suspended, nely divided catalyst in an axial path through said zones while preventing intermingling of the two streams in the conversion Zone but permitting catalyst to pass from the feed stream to the gas stream in the regeneration Zone, removing heat from the gases in the regeneration Zone whereby said Zone is cooled to regeneration temperature, withdrawing converted hydrocarbons and unregenerated catalyst from the central region of the regenerationifzonef and withdrawing .converted hydrocarbons `andtregenerated 1 catalyst from .the peripherallregion `of thefregeneration zone.

6. In the art of Ic'ataly-tic'all'y "converting hydrocarbons, the steps which comprise-passing a stream of hydrocarbonieed' stock into a conversion rzone'. andithen-into-'a regeneration zone; vintroducing nely divided catalyst linto the conversion zone, passingl a stream. of.hot flaming regeneration gases in a helical path around the hydrocarbon stream in saidconversion zone and in` heatexchange-relation v therewith, thereby i-to heat `saidhydrocarbon stream to conversiontemperature; fcooling the ,Y regeneration gases to l -regeneration temperature as they pass from the conversion zone into the regeneration zone, Withdrawing converted hydrocarbons and unregenerated catalyst from the central regionvof the regeneration Zone, and withdrawing converted hydrocarbons and regenerated catalyst from the peripheral region of the regeneration zone.

7. In the art of catalytically converting hydrocarbons, the Steps which comprise passing a stream of hydrocarbon feed stock into a conversion Zone and then into a regeneration Zone, introducing nely divided catalyst into the conversion Zone, passing a stream of hot iiaming regeneration gases in a helical path around the hydrocarbon stream in said conversion Zone and in heat exchange relation therewith, thereby to heat said hydrocarbon stream to conversion temperature, cooling the regeneration gases to regeneration temperature as they pass from the conversion Zone into the regeneration Zone, withdrawing converted hydrocarbons and unregenerated catalyst from the central region of the regeneration zone, withdrawing converted hydrocarbons and regenerated catalyst from the peripheral region of the regeneration zone, separating converted hydrocarbons from the regenerated catalyst, recycling the regenerated catalyst, separating converted hydrocarbons and unregenerated catalyst, revitalizing the unregenerated catalyst, and recycling the revitalized catalyst.

8. In the art of catalytically cracking a feed stock, the steps which comprise passing a stream of hydrocarbon cracking stock containing a suspended, nely divided catalyst into a cracking Zone and then into a regeneration Zone, passing a stream of hot combustion gases containing oxygen in a helical path around the hydrocarbon stream in said cracking zone and in heat exchange relation therewith, thereby to heat said hydrocarbon stream to a cracking temperature within the range of 800 to 1050 F., tangentially introducing a diluent stream into the combustion gas stream as it passes from the cracking zone to the regeneration zone t cool said combustion gases to a regeneration temperature within the range of 950 to 11.50 F., thereby to burn carbonaceous deposits from the catalyst in said regeneration zone, withdrawing cracked hydrocarbons and unregenerated catalyst from the central region of the regeneration Zone, and withdrawing regenerated catalyst from the peripheral region of the regeneration zone.

9. In the art of catalytically cracking hydrocarbons, the steps which comprise passing a stream of'gas oil having a boiling range of 400 to '750 F. containing suspended, finely divided cracking catalyst into a cracking zone and then into a regeneration zone, passing a stream of hot combustion gases containing oxygen in a helical path around the gas oil stream in said lo cracking vAzone :and in heatwexchange". relation therewith-'toa raise'lthe gasoil Ltb la cracking temperature within the' range-of 800'to 1050a F.,

maintaininga pressure of= 15 tof500-pounds-'per Asquare inch inthe cracking and regeneration Zones, regulating-.the velocity-1 off the gasoil stream Ato 1 provide a' cracking"- tirneof .from .001 second to lfminute, cooling--the helically-'moving rcombustion-gases to a temperature *ofL 950to '1150* F. as they pass ffromftheconversi-on zone tothe regeneration zone while permitting-'intermingling of lthefgas oil'stream vandv the rcombustion gas stream, thereby to: remove carbonaceous deposits `from" the* catalyst particles, withdrawing cracked hydrocarbons and unregenerated cata-I lyst from the central region of the regeneration zone, and withdrawing cracked hydrocarbons and regenerated catalyst from the peripheral region of the regeneration Zone.

10. In the art of cataiytically cracking hydrocarbons, the steps which comprise passing a stream of gas oil having a boiling range of 400 to 750'? F. containing suspended, nely divided silica-zirconiaJ catalyst into a cracking zone and then into a regeneration zone, passing a stream of hot combustion gases in a helical path around the gas oil stream in said cracking zone and in heat exchange relation therewith to raise the gas oil to a cracking temperature within the range of 800 to 10.50 F., maintaining a pressure of 15 to 500 pounds per square inch in the cracking and regeneration zones, regulating the velocity of the gas oil stream to provide a cracking time of from .001 second to 1 minute, introducing a tangential stream of nitrogen into the region surrounding the conversion zone concurrently with the helically-rnoving combustion gases to cool said combustion gases to a conversion temperature Within the range of 950 to 1150 F., introducing sucient oxygen with the nitrogen to maintain an oxygen content of from .5 to 5 per cent in the gases at the periphery of the regeneration zone, withdrawing converted hydrocarbons and unregenerated catalyst from the central region of the regeneration zone, and withdrawing regenerated catalyst from the peripheral region of the regenerated Zone.

11. A reactor for use in the catalytic conversion of hydrocarbons which comprises, in combination, an elongated generally cylindrical Vessel, a tube of heat exchange material disposed Within said vessel and secured to one end thereof, a conduit for introducing feed stock through said end of the vessel t0 the interior oi said tube, a tangentially disposed pipe for introducing hot gases into the interspace between said tube and said vessel, heat insulating material covering the exterior of said vessel at said one end thereof, a tangential pipe extending into the central region of said vessel and spaced from said tub-e and said heat insulating material, an enlarged outlet disposed at the other end of said Vessel having an inwardly-protruding guide portion for collecting gases from the central region of said vessel, and an outlet for collecting gases from the interspace between said vessel and said guide member.

12. A reactor for use in the catalytic conversion of hydrocarbons which comprises, in combination, an elongated generally cylindrical vessel, a tube of heat. exchange material disposed within said vessel and secured to one end thereof,

a conduit for introducing feed stock through said ritially around said conduit and communicating 'pipe for introducing combustion gases into the interspace between said tube and said Vessel, heat insulating material covering the exterior of said 'vessel at said one end thereof, a tangential pipe extending into the central region of said vessel and spaced from said tube and said heat insulat- .ing material, an enlarged outlet disposed at the other end of said Vessel having an inwardly- 'protruding guide portion for collecting gases from the central region of said vessel, and an outlet for collecting gases from the interspace between said vessel and said guide member.

GEORGE GROVER OBERFELL. GEORGE N. CADE.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name v Date 1,856,801 Atwell May 3, 1932 1,928,494 Irwin et al. Sept. 26, 1933 1,990,697 Keeling Feb. 12, 1938 

1. IN THE ART OF CATALYTICALLY CONVERTING HYDROCARBONS, THE STEPS WHICH COMPRISE PASSING A STREAM OF HYDROCARBON FEED STOCK CONTAINING SUSPENDED, FINELY DIVIDED CATALYST INTO A CONVERSION ZONE AND THEN INTO A REGENERATION ZONE, PASSING A STREAM OF HOT REGENERATION GASES IN A HELICAL PATH AROUND THE HYDROCARBON STREAM IN SAID CONVERSION ZONE AND IN HEAT EXCHANGE RELATION THEREWITH, THEREBY TO HEAT SAID HYDROCARBON STREAM TO CONVERSION TEMPERATURE, COOLING SAID GASES TO REGENERATION TEMPERATURE AS THEY PASS FROM THE CONVERSION ZONE INTO THE REGENERATION ZONE, WITHDRAWING CONVERTED HYDROCARBONS AND UNREGENERATED CATALYST FROM THE CENTRAL REGION OF THE REGENERATION ZONE, AND WITHDRAWING CONVERTED HY- 